stench vs malodour

stench and malodour both are nouns.

Word	Noun	Adjective	Verb	Adverb
stench	Yes	No	No	No
malodour	Yes	No	No	No

As nouns, stench and malodour are synonyms defined as:

Other synonyms of stench include fetor, foetor, malodor, mephitis, reek, stink.

stench (noun)	malodour (noun)
a distinctive odor that is offensively unpleasant	a distinctive odor that is offensively unpleasant